The present invention relates to a method of and apparatus for non-contact conditioning of tools, for truing, dressing or cleaning tools such as a grinder or a cutting tool, by using a laser. More particularly, this invention relates to a grinder used for side machining of a scroll (spiral vane) built in an air-conditioning scroll compressor, or for finish machining of a mold.
One of the tools used for side machining of a scroll built in a scroll compressor is an end mill. FIG. 25 shows an end mill 100 used for side machining of the scroll (spiral vane). In FIG. 25, 102 denotes a cutting edge, 103 denotes a groove between the cutting edges 102, 104 denotes a core diameter, 105 denotes a shank serving as a portion which holds the end mill 100 with a jig or the like, and 106 denotes an angle of torsion of the cutting edge. FIG. 26 shows a scroll 107, being a workpiece to be machined, and the scroll 107 has a scroll tooth 108.
When side machining of the scroll tooth 108 of the scroll 107 is to be carried out by the end mill 100, the shank 105 of the end mill 100 is fitted to a rotation unit such as a motor, to rotate the end mill 100 by the rotation unit. At this time, the scroll 107 or the end mill 100 is shifted so as to follow the scroll shape, while the cutting edge 102 of the end mill 100 is brought into contact with the side face of the scroll tooth 108, thereby side machining of the scroll tooth 108 is carried out.
In the side machining by the end mill 100, however, the position where the cutting edge 102 contacts with the machined surface of the scroll tooth 108 changes due to the torsion of the cutting edge 102. Particularly, as the angle of torsion 106 decreases, the change of the contact position of the cutting edge 102 increases. As described above, in the side machining by the end mill 100, since the distance between the position where the shank 105 is fitted and the position where the cutting edge is brought into contact with the scroll tooth changes largely, the machining load varies largely, causing a problem in that high machining accuracy cannot be ensured. With a small-diameter end mill 100 having a large groove 103 and a small core diameter 104, the rigidity becomes low, and the end mill 100 bends, causing a problem in that the machining accuracy decreases.
Therefore, for this kind of machining, a grinder is often used. An ordinary grinder in which a binder is formed of vitrified or resin, is formed by mixing and stirring abrasive grains and the binder powder, followed by molding into a desired shape, and sintering the molded article. Therefore, minute holes exist therein, and hence the chips discharging property is not so bad. On the other hand, an electrodeposited grinder is produced by holding the abrasive grains by plating, and hence minute holes existing in the ordinary grinder do not exist, thereby deteriorating the chips discharging property.
FIG. 27 shows a columnar electrodeposited grinder 109 used for side machining of the scroll. In FIG. 27, 110 denotes a columnar base metal, 111 denotes a plating layer formed of nickel or chromium on the side face of the base metal 110, and 112 denotes abrasive grains of CBN or diamond arranged in one layer on the surface of the plating layer 111, and the abrasive grains 112 are put together at random and fixed on the plating layer 111.
When side machining of the scroll tooth 108 of the scroll 107 is to be carried out, using such an electrodeposited grinder 109, a portion of the grinder base metal 110 of the electrodeposited grinder 109 where the abrasive grains 112 are not electrodeposited is fitted to a rotation unit such as a motor, and the electrodeposited grinder 109 is rotated by the rotation unit. At this time, the electrodeposited grinder 109 or the scroll 107 is shifted so as to follow the scroll shape, while the abrasive grains 112, being the cutting edge, are brought into contact with the side face of the scroll tooth 108, thereby side machining of the scroll tooth 108 is carried out.
In the above electrodeposited grinder 109 in the conventional art, since the abrasive grains 112 are put together at random and fixed on the whole surface of the grinder, lots of abrasive grains as the cutting edge work on the machined surface, regardless of the existence of truing, thereby causing a problem in that the machining load is large. Particularly, since a small-diameter grinder has small shaft rigidity, it easily deforms, and has a problem in that the grinder bends to decrease the machining accuracy, or the grinder life is shortened, due to an increase of the machining load.
As described above, in the conventional electrodeposited grinder, since the abrasive grains are put together at random on the whole surface of the grinder, lots of abrasive grains as the cutting edge work on the machined surface, to increase the machining load, thereby it is difficult to obtain high machining accuracy. The conventional electrodeposited grinder has also poor chips discharging property.
In JISB4130 and JISB4131 in the JIS Standard, there is an indication relating to the grain size of abrasive grains of the CBN or diamond electrodeposited grinder, and the shape of the grinder. This indication, however, relates to the grain size of the abrasive grains 112 and the shape of the grinder base metal 110, and does not indicate the arrangement of the abrasive grains 112 on the surface of the grinder base metal 110.
Techniques relating to the truing method and the dressing method of the grinder are shown in JISB4134, JISB4135, JISB4136 or JISB4137 in the JIS Standard. These are for installing tools for truing or dressing so as to come in contact with the grinder to carry out truing and dressing.
These conventional art shown in the JIS Standard is a method for bringing the tool into contact with the grinder, and hence machining resistance is produced at the time of truing or dressing, causing unintended exhaustion of the cutting edge, dropout of abrasive grains or exhaustion of the binder, and further there is a problem of short life span of the tool. Further, there is a disadvantage in that deformation or cracking may occur with respect to a grinder with a small-diameter shaft having low rigidity, a grinder with a thin blade, or a small-diameter end mill.
Therefore, there has been proposed a technique for performing non-contact truing or dressing, using a laser beam. The technique relating to the non-contact truing or dressing is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-285971 shown in FIG. 28.
In this conventional art, at either a time of stopping or rotating a grinder 113, a laser beam is irradiated from a laser oscillator 115 to a grinder use plane 114a or a grinder auxiliary use plane 114b through a lens 116, to dissolve and evaporate a binder, to thereby adjust the amount of abrasive grains to be protruded and the outline of the abrasive grains. The grinder use plane 114a or the grinder auxiliary use plane 114b is observed by a portable confocal laser microscope 117. A feedback mechanism 118 determines the optimum conditions of the maximum laser output and pulse width to obtain a desired amount to be protruded and the optimum conditions of the laser irradiation position to obtain a desired grinder outline, and feeds back the determined optimum conditions to the laser oscillator 115.
In the conventional non-contact dressing and truing methods, it is disclosed that only the binder on the use plane of the grinder or on the auxiliary use plane of the grinder is dissolved and evaporated without damaging the abrasive grains, by using a laser beam having a wavelength other than the wavelength at which absorption of infrared rays and ultraviolet rays and selective absorption of impurities take place, to thereby control the amount of abrasive grains to be protruded and the grinder outline. However, control of a difference in grain size of the abrasive grains and a difference in height of working abrasive grains of the grinder is not disclosed therein.
It is an object of the present invention to obtain a method of and apparatus for non-contact conditioning of tools, to make highly accurate and highly efficient machining possible, by making it possible to carry out truing of a grinder which adjusts the number of working abrasive grains actually involved in machining and the shape of the abrasive grains, truing of a cutting edge of a cutting tool, dressing for adjusting the amount of abrasive grains to be protruded, or cleaning for removing attachments adhered on the grinder in a non-contact manner.
It is another object of the present invention to obtain a grinder in which the machining load is decreased to make highly accurate machining possible and the chips discharging property is improved.
The non-contact conditioning method according to this invention is a non-contact conditioning method of tools for carrying out truing of a grinder by irradiating a laser beam onto the grinder as a tool, wherein truing of the grinder is carried out by irradiating the laser beam onto the abrasive grains on the outermost periphery of the grinder from the tangential direction of the grinder.
According to this invention, since truing of a grinder is carried out by irradiating the laser beam onto the abrasive grains on the outermost periphery of the grinder from the tangential direction of the grinder, it becomes possible to adjust the number of working abrasive grains and the shape of the abrasive grains highly accurately, without damaging the binder, thereby enabling highly accurate and highly efficient machining. Also, since it is possible to increase the number of working abrasive grains, the sharpness of the grinder is stabilized, thereby contributing in extending the life span of the grinder. It is also possible to control the grinder in an optional shape.
The non-contact conditioning method of tools according to the next invention is a non-contact conditioning method of tools for carrying out truing of a cutting tool by irradiating a laser beam onto the cutting tool. The truing of the cutting tool is performed by irradiating the laser beam onto the cutting edge on the outermost periphery of the cutting tool from the tangential direction thereof.
According to this invention, since truing for conditioning the shape of an edge of the cutting tool is carried out by irradiating the laser beam onto the cutting edge on the outermost periphery of the cutting tool from the tangential direction thereof, it is possible to adjust the shape of the edge or the height of the edge of the cutting tool highly accurately, thereby enabling highly accurate and highly efficient machining.
The non-contact conditioning method of tools according to the next invention is a non-contact conditioning method of tools for carrying out dressing of a grinder by irradiating a laser beam onto the grinder as a tool. Dressing of the grinder is carried out by selectively irradiating the laser beam so that the laser beam is irradiated only to the binder portion of the grinder.
According to this invention, the laser beam is selectively irradiated so that the laser beam is not irradiated onto the abrasive grains of the grinder, but irradiated only to the binder portion, thereby dressing for adjusting the amount of the abrasive grains to be protruded is carried out. As a result, the amount of the abrasive grains to be protruded can be adjusted highly accurately, thereby enabling highly accurate and highly efficient machining.
The non-contact conditioning method of tools according to the next invention is a non-contact conditioning method of tools for carrying out cleaning of a grinder by irradiating a laser beam onto the grinder as a tool. Cleaning of the grinder is carried out by selectively irradiating the laser beam so that the laser beam is irradiated only to the attachments adhered on the grinder.
According to this invention, the laser beam is selectively irradiated so that the laser beam is irradiated only to the attachments such as chips adhered on the grinder to remove the attachments, thereby cleaning of the grinder is carried out. As a result, the attachments such as chips adhered on the grinder can be reliably removed, without damaging the abrasive grains and the binder, thereby enabling highly accurate and highly efficient machining.
The apparatus for non-contact conditioning of tools according to the next invention is an apparatus for non-contact conditioning of tools which carries out truing of a grinder by irradiating a laser beam onto the grinder as a tool. The apparatus comprises a laser beam irradiation unit which irradiates the laser beam onto abrasive grains on the outermost periphery of the grinder from the tangential direction of the grinder, an observation unit which observes the laser-beam-irradiated portion of the grinder, and a control unit which controls the laser beam irradiation unit so as to obtain a predetermined number of working abrasive grains or a predetermined shape of the abrasive grains, based on observed output of the observation unit.
According to this invention, truing is carried out so as to irradiate the laser beam onto the abrasive grains on the outermost periphery of the grinder from the tangential direction of the grinder, so that a predetermined number of working abrasive grains or a predetermined shape of the abrasive grains is obtained, based on the observed output of the observation unit. Therefore, the number of working abrasive grains and the shape of the abrasive grains can be adjusted highly accurately without damaging the binder, thereby enabling highly accurate and highly efficient machining. Also, since it is possible to increase the number of working abrasive grains, the sharpness of the grinder is stabilized, thereby contributing in extending the life span of the grinder. It is also possible to control the grinder in an optional shape.
The apparatus for non-contact conditioning of tools according to the next invention is an apparatus for non-contact conditioning of tools which carries out truing of a cutting tool by irradiating a laser beam onto the cutting tool. The apparatus comprises a laser beam irradiation unit which irradiates the laser beam onto a cutting edge on the outermost periphery of the cutting tool from the tangential direction of the cutting tool, an observation unit which observes the portion of the cutting tool irradiated by the laser beam, and a control unit which controls the laser beam irradiation unit so as to obtain a predetermined shape of the edge, based on observed output of the observation unit.
According to this invention, truing is carried out so as to irradiate the laser beam onto the cutting edge on the outermost periphery of the cutting tool from the tangential direction of the cutting tool, so that a predetermined shape of the edge is obtained, based on the observed output of the observation unit. Therefore, the shape of the edge of the cutting tool or the height of the edge can be adjusted highly accurately, thereby enabling highly accurate and highly efficient machining.
The apparatus for non-contact conditioning of tools according to the next invention is an apparatus for non-contact conditioning of tools which carries out dressing of a grinder by irradiating a laser beam onto the grinder as a tool. The apparatus comprises a laser beam irradiation unit which irradiates a laser beam onto the grinder, an observation unit which observes the laser-beam-irradiated portion of the grinder, and a control unit which controls the laser beam irradiation unit to selectively irradiate the laser beam so that the laser beam is irradiated only to a binder portion of the grinder, and controls the laser beam irradiation unit so as to obtain a predetermined amount of the grinder to be protruded, based on observed output of the observation unit.
According to this invention, since dressing for selectively irradiating the laser beam is executed so that the laser beam is irradiated only to the binder portion of the grinder and a predetermined amount of the grinder to be protruded is obtained, based on the observed output of the observation unit, the amount of the grinder to be protruded can be adjusted highly accurately, thereby enabling highly accurate and highly efficient machining.
The apparatus for non-contact conditioning of tools according to the next invention is an apparatus for non-contact conditioning of tools which carries out cleaning of a grinder by irradiating a laser beam onto the grinder as a tool. The apparatus comprises a laser beam irradiation unit which irradiates a laser beam onto the grinder, an observation unit which observes the laser-beam-irradiated portion of the grinder, and a control unit which controls the laser beam irradiation unit to selectively irradiate the laser beam so that the laser beam is irradiated only to attachments adhered on the grinder, based on observed output of the observation unit.
According to this invention, since cleaning for selectively irradiating the laser beam is executed so that the laser beam is irradiated only to the attachments such as chips adhered on the grinder, based on the observed output of the observation unit, the attachments adhered on the grinder can be reliably removed without damaging the abrasive grains and the binder, thereby enabling highly accurate and highly efficient machining.
The grinder according to the next invention is a grinder in which abrasive grains are fixed on the plane of a disc-shaped base metal or on the circumference of a columnar base metal, in which the abrasive grains are arranged helically on the plane of the base metal on which the abrasive grains are fixed.
According to this invention, since the abrasive grains are arranged helically, the abrasive grains are arranged so as to continuously machine a surface of a workpiece to be machined, thereby improving the accuracy of the machined surface. Also, the interval from when one abrasive grain has come in contact with the workpiece until the next abrasive grain comes in contact with the workpiece becomes short, and the fluctuation in the machining load decreases, thereby enabling highly accurate machining. Further, the chips discharging property is improved due to a decrease in the number of the abrasive grains, and the machining load also decreases.
The grinder according to the next invention is a grinder in which abrasive grains are fixed at random on the plane of a disc-shaped base metal or on the circumference of a columnar base metal. The grinder is subjected to truing by the irradiation of a laser beam and includes a plane which fixes abrasive grains, on which a groove is formed by the irradiation of the laser beam.
According to this invention, truing is carried out by the irradiation of the laser beam to equalize the height of the abrasive grains, and a groove is formed on the plane which fixes the abrasive grains by the laser irradiation. Therefore, accuracy of the machined surface and the chips discharging property are improved, and the machining load decreases.
Other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.